1. Technical Field
This invention relates to a ventilation device for a vehicle roof window, and particularly to a sun roof which can be opened.
2. Description of the Prior Art
Vehicles which are not moving, moving relatively slowly, or are exposed to calm or only weakly blowing winds, are not cooled by relatively large masses of air flowing over them. The interior of the vehicle then heats up rapidly, especially in strong sunshine. This heat is oppressive to the body of a vehicle occupant; and cannot be greatly reduced, even by opening the window in the roof of the vehicle. By vehicle roof is understood here the whole zone of the vehicle body is provided with window surfaces, and especially the substantially horizontal roof surface. A certain remedy for such heating can be given by a ventilating blower or fan. But these ventilating blowers have, because of the very limited cross section dimensions of the ventilation ducts, through which relatively great amounts of air must be carried, the disadvantage of high power consumption, which greatly drains the battery which is generally used as a power source. When the vehicle is not running and the battery is not being recharged, these ventilating blowers cannot be used for long periods of time. Such ventilating blowers also have the disadvantage of producing local drafts, since the air exiting from the ventilator ducts must necessarily be concentrated in areas of the vehicle, or a great many air exits would have to be provided, which would cause difficulties in placing the ducts, as well as high costs.
In dwelling cars (mobile homes, campers) force-ventilated roof openings are provided in the roof, which in their closed position, through hidden ventilation slits, in the frame or in a hood-shaped cover, allow a constant exchange of air. To improve the exchange of air in such roof openings for mobile homes when the roof window is in the closed position, there has been proposed in German Disclosure No. 3,003,224, a motor-driven ventilator fan in the area of the openings for constant ventilation, which cannot be closed, is integrated into the hood of the roof opening, which can be opened. Such a hood is generally built as a double shell. It consists of a cover and a bottom shell, so that the heat-insulating effect of a double glazing is obtained. Here, either the space between the two shells forms the permanent ventilation duct, or the constant ventilation takes place through special ventilation slits in the rim of the hood, which form, with the frame of the opening, a water-tight construction. With these known hoods which are actively force-ventilated in their closed position, the fan itself is fastened to the hood, which can be opened. The fan is fastened on the cover of the hood, if the force-ventilated air is conducted between the cover and bottom of the hood, or on the bottom of the hood, if a ventilation duct is provided running around the side of the hood rim. In the first case, the active force ventilation works only in combination with a double-shell roof hood. In the second case, the fan blades, borne on long stems, must be led through the surrounding ventilation channel, which must therefore be circular. In both cases, only with the roof hood closed is a sufficiently active forced ventilation of the vehicle obtained, since with the roof hood open, either the necessary high speed of air in the flow will lead to predominant flow of air from outside (in the first case), or because the fan blades, operating in near the rim of the opening, are effective only in the area of outside air. With the roof hood opened, therefore, only the outside air near the opening is circulated in the area of the opening itself, without the interior of the vehicle being either aired or deaerated. This disadvantage is tolerated, in the ventilation device known from German Disclosure No. 3,003,224, because there it is a matter of ventilated roof hoods, permanently in the closed position, for mobile homes. Another disadvantage of this known roof hood is the power consumption of the fan motor, which can be calculated in with the energy consumption plan of a mobile home.
From German Disclosure No. 2,943,970 is known a ventilation device of a different kind for force-ventilated roof openings of the kind mentioned. Accordingly, a ventilator, consisting of a fan motor and a fan wheel, is arranged on a stationary attachment support. This attachment support consists of hollow arms, tapering outward, through which the air, ejected by the fan, is fed to ventilation slits in the rim of the roof opening. This air conduction requires a relatively strong fan motor, and produces relatively high air speeds near the fan wheel, which are felt as drafts. The attachment support cannot be used for sun roofs for vehicles, which can be raised and/or pushed along, since sun roofs for vehicles could have no forced ventilation slits because their pane covers need to seal the outside environment from the inside of the vehicle.